1. Field of the Invention
The present invention relates to an analogue electronic clock and a motor control circuit which is suitably applicable to an analogue electronic clock or the like.
2. Description of the Prior Art
Conventionally, an analogue electronic clock which is configured to rotationally drive time hands for displaying time such as a hour hand, a minute hand and the like using a motor has been used. The analogue electronic clock includes the motor which rotationally drives the time hands and a motor control circuit which controls the rotation of the motor, wherein by rotationally driving the motor by the motor control circuit based on time signals which constitute references of time, the time hands can perform a time display.
In the electronic clock which is described in JP-B-61-15385, for rotationally driving the motor which serves to drive the time hands, the motor is rotationally driven by selectively using a plurality of main drive pulses, and when a rotation detection circuit detects that the motor is not rotated, the motor is rotationally driven using an auxiliary drive pulse having a larger pulse width than widths of the above-mentioned respective main drive pulses thus realizing the rotational driving with minimum energy corresponding to a motor load.
For example, a load such as an electronic clock calendar cannot be driven with the main drive pulse having a minimum pulse width (minimum energy) and hence, after performing the rotational driving with the correction drive pulse temporarily, the rotational driving is performed by changing the main drive pulse to the main drive pulse having the larger energy (the larger pulse width) than the minimum energy drive pulse (pulse-up).
When the large load is continued, the rotational driving with the main drive pulse having the large pulse width which is proportional to the load is continued. When the large load disappears and the load becomes small, upon detecting that the motor is stably driven for a fixed time with the drive pulse, the motor is rotationally driven by changing the main drive pulse to the main drive pulse having small energy (small pulse width) (pulse-down) thus realizing the low power consumption.
However, in performing the pulse-down along with the decrease of the load, the motor is configured such that when the motor is stably driven with the main drive pulses by predetermined times at this point of time, the pulse-down is performed. Accordingly, the fact that the normal rotational drive operation with the main drive pulse at this point of time is continuously performed predetermined times is counted by a counter circuit, and when the counter circuit counts the rotational drive operation the above-mentioned predetermined times, the pulse-down is performed thus changing the main pulse width to the main drive pulse having the pulse width corresponding to the magnitude of the load.
Accordingly, the counter circuit is necessary in the analogue electronic clock and hence, in an attempt to form only an electronic circuit which constitutes a motor control circuit or an electronic circuit which constitutes an electronic clock including the motor control circuit into an integrated circuit (IC), there exists a drawback that an IC chip size cannot be reduced.
Further, the pulse width to be changed, the pulse-width changing timing and the like in performing the pulse-down differ for respective products and hence, there exists a drawback that the circuit constitution becomes complicated to cope with the respective products.
Further, in performing the pulse-down, it is necessary to perform the rotational driving with the main drive pulse having the pulse width larger than the necessary pulse width predetermined times and hence, there exists a drawback that the power consumption is increased. Accordingly, in an electronic clock or the like which uses a battery as a power source, there arises a drawback that the battery lifetime becomes short and the number of battery change is increased thus making the battery changing operation cumbersome.
It is an object of the present invention to provide a motor control circuit which can rotationally drive a motor with a main drive pulse having a pulse width corresponding to a motor load with the simple constitution without using a counter circuit.
Further, it is an object of the present invention to provide a motor control circuit which can realize the low power consumption.
Further, it is an object of the present invention to provide an analogue electronic clock which can rotationally drive a motor with a main drive pulse having a pulse width corresponding to a motor load with the simple constitution without using a counter circuit.
Further, it is an object of the present invention to provide an analogue electronic clock which can realize the low power consumption.